World stocks were mixed to start the week on Monday, as investor enthusiasm in Asia failed to spread to Europe and Wall Street, where geopolitical worries weighed on indices.

In Europe, stocks gave up early gains following a defiant reply to EU critics by Rome, which intends to stick to a controversial spending budget.

The dollar rose against major rivals, while oil prices edged lower, as investors also tracked geopolitical tensions, notably in response to the murder of Saudi critic Jamal Khashoggi.

Italy's coalition government told the European Union it would stick to its high-spending draft budget but would also scrupulously avoid going over its own debt and deficit limits.

"The figure of 2.4 percent (deficit to GDP ratio in 2019) is a ceiling that we have solemnly undertaken to respect," Prime Minister Giuseppe Conte told journalists after the coalition sent its pledge in a letter to the EU.

The coalition was under some pressure following a cut in its credit rating by Moody's Investors Service on Friday.

"Moody's have downgraded Italy's credit rating to one notch above junk status, but the agency lifted its outlook to stable from negative, so investors aren't afraid of another downgrade in the near-term," noted David Madden, market analyst at CMC Markets UK.

At the close on Monday, the Milan FTSE MIB index was off by 0.6 percent, after an initial rally petered out.

Geopolitics, uncertain waters

Meanwhile, as corporate earnings season continued in New York, Wall Street was also mixed, with gains among tech stocks lifting the Nasdaq but the Dow and S&P extending losses from last week.

Peter Cardillo of Spartan Capital told AFP geopolitical worries and the looming US congressional elections were making for rough seas.

"The situation with Saudi Arabia could be a problem," he said, referring to diplomatic controversy over the killing of journalist Jamal Khashoggi in Turkey.

"And as the mid-term elections approach it also causes uncertainties."

Earlier Monday, most Asian stock markets rose, with Shanghai surging more than four percent to build on a rally at the end of last week -- though traders remain cautious over China-US trade tensions.

Tokyo reversed early losses to end 0.4 percent higher, while Sydney fell.

While trade unrest simmers, investors are considering other brewing problems, including the United States saying it will pull out of a decades-old nuclear treaty with Russia.